Wire twisting apparatus

ABSTRACT

A rotatable member ( 105 ) has an aperture ( 115 ) substantially aligned with an axis of rotation of the member and through which a first length of wire ( 2   a ) may extend. A recess ( 117 ) is provided in the member. An engagement surface ( 131 ) is associated with the recess. With s first length of wire ( 2   a ) extending through the aperture and a second length of wire ( 7 ) extending across and adjacent to the first length of wire, rotation of the rotatable member will cause the engagement surface ( 131 ) to engage with the second length of wire ( 7 ) and twist the second length of wire around the first length of wire ( 2   a ) to form a twisted wire joint at least substantially within the recess and which includes a plurality of full turns of the second length of wire around the first length of wire.

FIELD OF INVENTION

This invention relates to an apparatus for twisting a length of wire around another length of wire to form a twisted wire joint. More particularly, although not exclusively, the invention relates to a mechanism for twisting a stay wire around a line wire in a fence mesh forming machine.

BACKGROUND Of THE INVENTION

Forms of fence mesh are known in which the wires forming the fence are knotted together at each or many wire intersections. In general, knotted fence mesh is stronger than wire fence in which the fence wires are not knotted together at their intersections and which is typically used in domestic or light industrial applications. Knotted fence mesh is used tor applications where additional strength is required, such as for containing larger or stronger animals such as horses or deer for example.

Knotted fence mesh with a rectangular or square mesh for example is typically formed from a number of generally parallel line wires, which will extend generally horizontally when the fence mesh is set in position between fence posts, and lengths of stay wire which extend laterally across the line wires at regular spacings (and generally vertically when the fence mesh is set in position). In machines for forming knotted fence mesh a number of continuous line wires are fed to a bed of the machine comprising a number of similar knot boxes, and stay wire is fed into the machine bed across the line wires. Such machines typically have a step-wise operation and form a series of knots along a length of stay wire at each intersection of the stay wire and the line wires at each operational step or “beat” of the machine. At each step or beat the line wires are advanced forward in parallel through the side by side knot boxes of the machine bed, stay wire is fed into the bed of the machine across the line wires at the knot boxes, at approximately 90° to the line wires in the case of a machine for forming rectangular fence mesh., a length of stay wire is cut, and simultaneously at each knot box at an intersection between the line wires and the stay wire a knot securing the stay wire to the line wire is formed.

A fence mesh forming machine is described in U.S. Pat. No. 6,668,869, the contents of which is incorporated herein by reference. That fence mesh machine is shown generally in FIGS. 1 a and 1 b.

FIG. 1 a shows a number of continuous line wires 2 and knot wires 3 being fed to a bed 4 of the machine 1, which bed has a plurality of side by side knot boxes 5. The line wires 2 enter the machine at its base, are turned through 90 degrees around rollers 6 and pass vertically through the knot boxes 5, One line wire 2 and one knot wire 3 pass through each knot box 5 with different orientations, A continuous stay wire 7 is projected across the bed of the machine via a stay wire feed apparatus comprising two aligned pairs of driven rollers 8 and a free-running guide sheave 8 a so as to transversely cross each of the knot boxes 5, thereby forming a plurality of stay wire-line wire intersections.

The machine 1 has a main drive roller 9 which pulls the completed fence mesh, through the knot boxes 5, the drive roller being driven by an electric motor 10. The completed fence mesh (indicated generally by reference numeral 11 in FIG. 1 b) then extends around a further roller 12, and would typically extend to a coiling machine or take-up unit (not shown) to form it into a coil tor ease of handling and transportation.

The knotted fence mesh forming machine 1 generally has a step-wise operation and forms a series of knots along the length of stay wire 7 at each line wire-stay wire intersection at each step or “beat” of the machine. At each step or beat the line wires 2 are advanced forward in parallel through the side by side knot boxes 5 in the machine bed 4 via the drive roller 9, a stay wire 7 is fed into the bed 4 of the machine across the line wires at the knot boxes 5, at 90° for forming square fence mesh as shown, a length of the stay wire 7 is cut, and simultaneously in each knot box 5 at each intersection between the line wires and the stay wire a knot securing the stay wire to the line wire is formed.

At each side of the fence mesh, the stay wire is generally twisted around the side line wires 2 a as in the completed fence mesh the stay wire does not extend beyond the side line wires. That is achieved using a wire twisting apparatus. With existing wire twisting apparatuses the twisted knots may loosen, or as the twisted knots are being formed the knot may move up the respective line wire,

Step-by-step operation of the wire twisting apparatus 21 of the machine of FIG. 1 a and 1 b is shown in FIGS. 1 c to 1 g. The wire twisting apparatus 21 comprises a rotatable member with an aperture 23 substantially aligned with an axis of rotation of the member and through which a line wire 2 a may extend. An engagement member 27 extends from the top surface of the rotatable member. Initially, as shown in FIG. 1 c, the line wire 2 a extends through the aperture 25, and the stay wire 7 extends transversely across and adjacent to the line wire. The stay wire extends past the engagement member. FIG. 1 d shows the wires after one rotation of the rotatable member, FIG. 1 e shows the wires after two rotations of the rotatable member, and FIG. 1 f shows the wires after three rotations of the rotatable member.

Due to the configuration of the rotatable member and engagement member 27, it is not possible for the rotatable member to undergo a full rotation and still twist the stay wire around the line wire, without forcing the stay wire 7 away from the rotatable member. That is because after substantially one turn of the rotatable member, the stay wire would impinge on the outside of the engagement member. Also, there is not sufficient room between die transversely-extending portion of the stay wire and the top of the rotatable member for the twisted wire joint to be formed downwardly.

The joint formed by fins configuration is shown in FIG. 1 g. The final twisted wire joint is rather loose, rather than being tightly twisted. Further, the transversely-extending portion of the stay wire is “kinked”, aid is moved a significant distance from its initial point of contact with the line wire. The fence formed in this manner can look uneven, and there can be problems during installation of the fence due to overstraining the fence to correct for the bends in the stay wires.

Wire twisting apparatuses are described in U.S. Pat. No. 3,722,554; U.S. Pat. No. 3,338,273; U.S. Pat. No. 3,985,162; and U.S. Pat. No. 4,223,705. Hand held winders are described in U.S. Pat. No. 4,392,518 and U.S. Pat. No. 4,634,100. The configurations of these apparatuses are generally such that again it would be necessary to force the cross wire away from the rotatable member to form a twisted wire joint, or it would be necessary to axially move the rotatable member relative to the longitudinal wire during the formation of the joint (such as described in U.S. Pat. No. 4,223,705). Tire result is that fee knot will be relatively loose or “kinked”, or additional time would be required to axially move the rotatable member.

As the fence mesh forming machine of FIGS. 1 a and 1 b has a step-wise operation, it will be appreciated that a “bottle-neck” in any step of the machine will have a significant overall effect on the speed and overall efficiency of the machine. Accordingly, it is desirable to minimise the duration of each step.

It is an object of at least preferred embodiments of the present invention to provide an apparatus for twisting a length of wire around another length of wire which addresses at least one of the disadvantages outlined above, or which will at least provide the public with a useful choice.

SUMMARY OF THE INVENTION

The term “comprising” as used in this specification and claims means “consisting at least in part of”; that is to say when interpreting statements in tins specification and claims winch include “comprising”, the features prefaced by this term in each statement all need to be present but other- features can also be present. Related terms such as “comprise” and “comprised” are to be interpreted in similar manner.

In accordance with a first aspect of the present invention, there is provided an apparatus for twisting a second length of wire around a first length of wire to form a twisted wire joint, the apparatus comprising a rotatable member comprising: an aperture substantially aligned with an axis of rotation of the member and through which a first length of wire may extend; a recess, at least a portion of which is substantially aligned with the aperture; and an engagement surface associated with the recess; wherein the apparatus is configured such that with a first length of wire extending through the aperture and a second length of wire extending across arid adjacent to the first length of wire, rotation of the rotatable member will cause the engagement surface to engage with the second, length of wire and twist the second length of wire around the first length of wire to form a twisted wire joint at least substantially within the recess and which includes a plurality of full turns of the second length of wire around the first length of wire.

Suitably, the apparatus is configured to form the twisted wire joint while allowing a remainder part of the second length of wire, other than the part in the twisted wire joint, to remain substantially undeformed. Advantageously, the apparatus does not require movement of the rotatable member along the first length of wire during the formation of the twisted wire joint or movement of the remainder part of the second length of wire along the first length of wire during the formation of the twisted wire joint.

The engagement surface may be configured to direct a free end of the second length of wire is the general direction of the aperture, during the formation of the twisted wire joint In a preferred embodiment, the apparatus is configured such that the second length of wire will have an initial point of contact with the first length of wire prior to, or as, the rotatable member is rotated, and the second length of wire can substantially maintain its initial point of contact with the first length of wire during the formation of the twisted wire joint, and the twisted wire joint will extend into the recess from the initial point of contact between the first aid second lengths of wire. Preferably, the recess terminates at a substantially planar surface of the rotatable member, and a portion of the remainder part of the second length of wire can remain substantially in contact with the generally planar surface during formation of the twisted wire joint.

The engagement surface may be angled and may extend substantially from an outer edge of the rotatable member toward the aperture in the rotatable member. Advantageously, the outer edge of the rotatable member defines an engagement portion to initially engage with the second length of wire upon rotation of the rotatable member. The recess may comprise a generally centrally-disposed arcuate wall portion that is positioned adjacent the aperture. Preferably, the aperture has a diameter, and the arcuate wall portion has a size sufficiently greater than the diameter of the aperture that the portion of the first wire extending through tire aperture is supported during the formation of the twisted wire joint, and sufficient clearance is provided in the arcuate wall portion to enable the twisted wire joint to be formed.

Suitably, the recess is generally segment-shaped, and a narrow portion of the generally segment-shaped recess is defined by the arcuate portion.

The engagement surface is preferably defined by a wall portion of the recess.

The apparatus preferably comprises a positioning member configured to position a tree end of the second length of wire such that rotation of the rotatable member will cause the engagement surface of the rotatable member to engage with the second length of wire. Advantageously, the positioning member is configured to bend a tree end of the second length of wire extending beyond a central portion of the rotatable member.

The positioning member may comprise a ramp portion that is configured to bend the free end of the second length of wire upon relative movement between the free end of the second length of wire and the positioning member.

The apparatus suitably comprises a cutting member to cut a free end of the second length of wire prior to rotation of the rotatable member.

The apparatus may comprise at least one support plate to assist in maintaining the wires adjacent one another during the formation of the twisted wire joint. The support plate suitably comprises a curved portion to assist in directing a free end of the second length of wire in the general direction of the aperture, upon rotation of the rotatable member.

The apparatus is preferably configured such that the first length of wire remains substantially undeformed during the formation of the twisted wire joint.

In accordance with a second aspect of the present invention, there is provided a fence mesh forming machine comprising: a machine bed arranged to pass a plurality of substantially parallel line wires therethrough; an apparatus arranged to deliver a stay wire across the line wires; and an apparatus as outlined in the first aspect above arranged to twist a free end of the stay wire around one of the line wires to form a twisted wire joint.

The apparatus is advantageously arranged to twist the tree end of the stay wire around an outermost line wire of the plurality of line wires.

The fence mesh forming machine may comprise two apparatuses as outlined in the first aspect above, arranged to twist the free ends of the stay wire around the two outermost line wires of the plurality of line wires to form twisted wire joints.

In accordance with a third aspect of the present invention, there is provided a method of twisting a second length of wire around a first length of wire to form a twisted wire joint, comprising: providing an apparatus as outlined in the first aspect above; extending a first length of wire through the aperture of the rotatable member; positioning a second length of wire across and adjacent to the second length of wire; and rotating the rotatable member such that the engagement surface engages with the second length of wire and twists the second length of wire around the first length of wire to form a twisted wire joint at least substantially within the recess of the rotatable member and which includes a plurality of full turns of the second length of wire around the first length of wire.

The method suitably comprises, prior to rotating the rotatable member, bending a free end of the second length of wire so that it is engaged by the engagement surface upon rotation of the rotatable member.

The invention consists in the foregoing and also envisages constructions of which the following gives examples only.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present invention are described by way of example only, with reference to the accompanying drawings In which:

FIGS. 1 a and 1 b are perspective views of an existing knotted fence mesh forming machine, which includes an existing apparatus for twisting an end of the stay wire around the side knot wire;

FIG. 1 c to If are overhead perspective views showing the formation of a twisted wire joint using the existing apparatus of the machine of FIG. 1 for twisting an end of the stay wire around the side knot wire;

FIG. 1 g is a side view of the apparatus of FIGS. 1 c to 1 g, showing the formed twisted wire joint;

FIG. 2 schematically shows part of a typical fence mesh formed by a machine such as that shown in FIGS. 1 a to 1 g;

FIG. 3 is a front overhead perspective view of part of a wire twisting apparatus in accordance with a preferred embodiment of the present invention;

FIG. 4 is a front view of the rotatable member of the apparatus of FIG. 3;

FIG. 5 is a front overhead perspective view of part of the preferred embodiment apparatus of FIG. 3, showing the stay wire ready to be twisted around the line wire;

FIG. 6 a is a side overhead perspective view showing the stay wire ready to be twisted around the line wire, and showing the support plates in position;

FIG. 6 b is a front overhead perspective view of the apparatus in the same configuration as FIG. 6 a;

FIG. 7 is a front perspective view of the rotatable member showing the support wire and line wire in position:

FIG. 8 a is a front perspective view showing the stay wire bent in position ready to be twisted by the rotatable member;

FIG. 8 b is a perspective view similar to FIG. 8 a showing the stay wire bent in position;

FIG. 9 is an underside perspective view similar to FIGS. 8 a and 8 b showing the stay wire in position and the support plates to support die wires;

FIG. 10 is an underside perspective view of one of the support plates showing a generally helical cut out to assist in twisting the wire;

FIG. 11 is a front perspective view showing a twisted wire joint once formed in the rotatable member;

FIG. 12 is a further view of the rotatable member with the twisted wire joint formed therein;

FIG. 13 is a an underside perspective view of the rotatable member;

FIG. 14 shows a side overhead perspective view of the preferred embodiment apparatus with the plates in a spaced apart configuration so that the twisted wire joint can be ejected;

FIG. 15 is a forward perspective showing the apparatus in die same configuration as FIG. 14;

FIG. 16 is an inverted perspective view of the preferred embodiment apparatus with a stay wire and line wire in. position;

FIG. 17 is a view similar to FIG. 16 but from a different side;

FIG. 18 is an inverted perspective view showing the stay wire following cutting and pushed along a ramp to a position from which it will be twisted;

FIGS. 19 a to 19 d show the steps of forming a twisted wire joint using the preferred embodiment apparatus;

FIG. 20 is an inverted perspective view of part of an alternative preferred embodiment apparatus with a stay wire and line wire in position;

FIG. 21 is an inverted perspective view of part of the apparatus of FIG. 20, showing the stay wire following cutting and pushed along a ramp to a position from which it will be twisted; and

FIG. 22 is an overhead perspective view of an existing wire twisting apparatus and preferred embodiment wire twisting apparatus, for comparison.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention has application in a knotted fence mesh forming machine such as that shown in FIGS. 1 a and 1 b. The general operation of that machine is described in U.S. Pat. No. 6,668,869, and will not be described in detail again here. The content of U.S. Pat. No, 6,668,869 is incorporated herein in its entirety by way of reference.

FIG. 2 shows the travel of wires through a fence mesh forming machine, such as that shown in FIG. 1. The line wires 2 travel in a generally parallel arrangement in a direction indicated by arrow L. After the line wires have travelled a predetermined distance, a stay wire 7 is fed across the Line wires hi the direction indicated by arrow S. A stay wire placer assembly may then locate and grip the stay wire. The stay wire would then be cut to a desired length, and knots indicated by X would be formed at all or a majority of the line wire-stay wire intersections. Generally, at each side of the fence mesh, the stay wire would be twisted around the line wire rather than being connected thereto by a knot Such a twisted wire joint is indicated generally by X′ in FIG. 2.

A preferred embodiment apparatus for twisting a second length of wire—in this case a stay wire 7—around a first length of wire—in this ease a line wire 2 a—is shown and described with reference to FIGS. 3 to 19. While the preferred embodiment apparatus has applications in other types of fence mesh forming machines, it also has application in the machine of FIG. 1. A preferred embodiment apparatus could be positioned in each area indicated by T in FIG. 1 to twist the free ends of the stay wires around the two outermost line wires in the fence mesh.

The preferred embodiment apparatus is indicated generally by reference numeral 101. As indicated In FIG. 3, the wire twisting mechanism 101 includes a bed 103, and a rotatable member 105 which is rotatable relative to the bed about an axis AA which extends through a centre of the rotatable member 105 (FIG. 4).

As can be seen more clearly in FIG. 4, the rotatable member 105 includes a body portion 107 having an arcuate wall portion with an enlarged upper shoulder 109 above the arcuate wall portion and an enlarged lower shoulder 111 below the arcuate wall portion. An upper surface 110 of the body portion preferably comprises a substantially planar surface. A transversely-extending portion of the stay wire, which defines a remainder portion of the stay wire, will preferably remain substantially in contact with the surface 110 of the body portion in use.

The rotatable member also has a substantially cylindrical base portion 113 which extends into or below the bed 103 when the rotatable member Is mounted for rotation in the bed of the machine, and the base portion may carry a gear, pulley or the like for driving the rotation of the member.

An aperture 115 winch can be seen most clearly in FIGS. 7 and 8 a which is substantially aligned with the axis of rotation A-A extends through the centre of the rotatable member and is configured for receipt of and to support, a line wire 2 a.

In plan view, the enlarged upper shoulder 109 and upper portion of the body portion 107 has a substantially segment-shaped recess 117. The upper extremity of the recess Is defined by a substantially V-shaped opening in the surface 110. The inner, generally centrally-disposed, part of the recess is defined by an arcuate surface 119 above the central aperture 115. The arcuate surface preferably extends to about half of the depth of the body portion. The arcuate surface 119 is sufficiently larger than the aperture 115 that die twisted wire joint can be formed within the arcuate surface of the recess. The portion of the recess defined by the arcuate surface 119 is substantially aligned with the aperture 115.

A wall 121 of the recess extends from the arcuate surface 119 and terminates at an outer edge of foe body portion. The wall 121 also diverges to terminate at the base of the body portion adjacent the enlarged lower shoulder. The opposite wall 123 of the recess tapers upwardly and outwardly from the arcuate surface and towards the upper shoulder 109. The wall 123 terminates in an outer edge of the body portion, which defines a hook or engagement portion 125 that extends outwardly into the upper shoulder from the wall 123 at an angle to the wall 123. The engagement portion preferably has a non-radial orientation as shown. The hook or engagement portion 125 has the purpose described below.

Adjacent the wall 121, the body portion 107 has a perimeter defined by substantially parallel upper and lower edges defined by the upper and lower shoulders 109, 111. Adjacent the wall 123, the perimeter of the body portion has tapering upper and lower edges defined by a surface 127 which slopes downwardly and inwardly from the upper shoulder 109 and a surface 129 which slopes upwardly and inwardly from the lower shoulder 111. That portion of the hub terminates at or near the arcuate portion 119.

In operation, the rotatable member 105 is configured to rotate in a clockwise manner about the central axis AA; as indicated by arrow R in FIG. 3. It will be appreciated that the features of the rotatable member could be reversed so that the rotatable member will function when rotating in a counter-clockwise direction. An engagement surface 131 extends from the enlarged upper shoulder 109 at the engagement portion 125, and is angled downwardly and inwardly towards the centre of the body portion, and preferably terminates adjacent the upper edge of the aperture 115. The engagement surface 131 is defined by the edge of the wail portion 123, more particularly by the intersection of the wall portion 123 and surface 127.

Rotation of the rotatable member 105 will be achieved through the operation of a drive mechanism 133 such as an electric motor. The rotatable shaft of the electric motor may extend beneath the bed 103 and may be operatively connected to the rotatable member via a gear or pulley arrangement or similar. In a preferred embodiment, a gear is connected to the base of the rotatable member 105, and a further gear is connected to the shaft of the motor 133, with an idler gear interconnecting the two other gears. The motor may be controlled via a control system which preferably controls the operation of other parts of the fence mesh forming machine.

A cutter 135 is provided adjacent the rotatable member 105. The cutter includes a channel 136 which, when the stay wire is delivered into or out of the apparatus, receives part of the stay wire. This is shown in FIG. 5 and in inverted FIGS. 16 and 17.

As shown in FIGS. 6 a and 6 b, the apparatus includes first and second support plates 137, 139. The first support plate 137 includes an aperture or recess 141 for receipt of the stay wire 7 and to assist in supporting the stay wire 7, as well as a recess or aperture 143 for receipt of the line wire 2 a and to assist in supporting the line wire.

The support plates 137, 139 may be movable between the engagement position shown in FIG. 6 b and a spaced apart position shown in FIG. 15. The support plates may be hydraulically actuated for example, and may be moved by respective drive bars 145, 147. The cutter 135 is preferably also operably connected to drive bar 145 so that it is moved concurrently with the first support plate.

As shown in FIGS. 9 and 10, the underside of the first support plate 137 is preferably provided with a shaped generally helical or curved cut out or recess 149, which assists in forming the top of the twisted wire joint into the correct shape.

During operation of the machine, following the formation of a line of line wire-stay wire knots, the line wires are moved one step through the machine In the direction indicated by arrows L in FIGS. 3 and 5, A stay wire 7 is fed across the line wires, using the mechanism described in U.S. Pat. No. 6,668,869 for example, and may be held in position by a stay wire placer assembly (not shown) to locate and grip the stay wire. At each edge of the fence mesh, a preferred embodiment apparatus 101 will be provided. The function of the apparatuses is to twist the stay wire around tire two outermost line wires 2 a (one on either side of the fence mesh).

Initially, the support plates 137. 139 of each apparatus 101 will be in the spaced apart configuration, and a line wire 2 a will extend upwardly through the aperture 115 in rotatable member. The stay wire is propelled to extend from one apparatus 101 to the other. In each apparatus 101, the stay wire will extend across the upper surface of the rotatable member 105, through the channel 136 in fee base of the cutter 135, and preferably into a fixed member 106 (or out of the fixed member 106 at the side of the machine from which the stay wire is fed). This is seen most clearly in the inverted views of FIGS. 16 and 17. The wires will Initially be in the position shown in FIGS. 5 and 16, with the stay wire 7 extending transversely across and adjacent to the line wire 2 a. As shown, the stay wire 7 suitably extends transversely across me entire rotatable member, to be cut by the cutter 135.

The following description will be for one apparatus 101 only, however it will be appreciated that m the fence mesh forming machine two such apparatuses could be operated concurrently.

The drive bars 145, 147 are moved to move the support plates 137, 139 towards one another to bring them to the position shown in FIG. 6 a and 6 b. As the cutter 135 is also operatively connected to the drive bar 145, that also moves tire cutter, which results in the cutting of the stay wire to a desired length. The toward movement of die cutter 135 and support plate 137 pushes the stay wire towards the line wire 2 a and down a ramp 104 a which in the embodiment shown is part of a positioning member 104 which is feed relative to the bed 103 of the machine, to bend the fee end of the stay wire 7 that extends beyond a central portion of the rotatable member. Once that movement is completed, the stay wire will be In the position shown in FIGS. 8 a, 8 b, 9, 17, 18, and 19, wherein the free end of the stay wire 7 has been bent as a result of movement down, the ramp 104 a so it is in a position where it will be engaged upon rotation of the rotatable member.

While the ramp is shown as being in an upward direction in FIGS. 16 to 18, it will be appreciated that those figures are inverted and accordingly the ramp will extend downwardly in the apparatus.

Once the support plates have moved to the positions of FIGS. 6 a, 6 b, 9, 17 and 18, the stay wire 7 is supported against the line wire 2 a by the edge of the aperture 141, and the line wire 2 a is supported in the aperture 115 and the aperture 143 against the face of tire support plate 139.

The motor 133 is then operated to cause clockwise rotation of the rotatable member 105 such as shown by arrow R in FIG. 3, As the rotatable member rotates, the bent free end of the stay wire will initially be engaged by the hook or engagement portion 125, and further rotation of the rotatable member will result in the twisting of the stay wire about the line wire 2 a. The line wire 2 a will be held stationary as the rotatable member is rotated. The helical or curved recess 149 in the underside of the second support plate 139 shown in FIGS. 9 and 10 causes the free end of the stay wire to initially move downwardly as it is rotated about the line wire 2 a. The engagement surface 131 of the rotatable member which begins with the engagement portion 125 also results in downward movement of the tree end of the stay wire in the general direction of the aperture 115 to assist in the formation of the twists.

The apparatus forms a twisted wire joint wherein the stay wire is twisted around the line wire which is still substantially straight, ie the line wire remains substantially undeformed. The portion of the rotatable member between surface 127 and 129 provides clearance for the free end of the wire as the twist is being formed.

Step-by-step formation of the twisted wire joint is shown in FIGS. 19 a-19 d. By way of example, the rotatable member 105′ of this Figure is a mirror image of the rotatable member described above, so is configured to be rotated in a counter-clockwise direction to engage the stay wire 7 and twist the free end of the stay wire around the line wire 2 a. However, the functionality and operation is otherwise the same. The configuration of support plate 137′ also differs in that it does not have the helical recess. That would instead be provided in the opposite support plate (not shown), as the rotatable member is configured for counter-clockwise rotation.

As can be seen in FIGS. 19 a-19 d, the preferred embodiment apparatus can form a twisted wire joint with multiple full tarns of the stay wire around the line wire. The twisted wire joint is formed at least substantially, and preferably completely, in the recess 117. As can be seen, during the formation of the twisted wire joint, the engagement surface 131 directs the free end of the stay wire in the general direction of the aperture 115 of the rotatable member as the twisted wire joint Is formed. That causes the knot to be formed downwardly within the recess 117, which forms a tightly compressed knot. Further, as can be seen from these Figures, it is not necessary for the transversely-extending remainder portion of the stay wire 7 to move from its initial point of contact with the line wire 2 a, The remainder portion of the stay wire remains substantially undeformed.

The transversely-extending portion of the stay wire 7 can maintain its initial point of contact with the line wire, and can remain in contact with the substantially planar upper surface 110 of the rotatable member 115.

The rotatable member will generally be rotated by at least 720° to form at least two .toll revolutions of the stay wire about the line wire. The arcuate portion of the recess 117 Is of sufficient depth that the required number of revolutions of twisted wire can be created. Preferably, the twisted wire joint will comprise three Ml turns of tire stay wire about the line wire. The depth of the arcuate recess is preferably such that it is a reasonably tight fit to form tire final revolution of the twisted wire joint, thereby forming a relatively tightly compressed twisted wire joint.

Once the twisted wire joint has been formed, the support plates 137, 139 and cutter 135 are retracted to the separated position shown in FIG. 15, and the formed line of knots and twisted joints can move upwardly another step, following which the process is repeated.

The preferred embodiments described above provide a relatively tight twisted wire joint between the fine wire arid stay wire, and the joint can be formed without any significant upward movement of the twisted slay wire on the respective line wire.

The above describes preferred embodiments, and modifications may be made thereto without departing from the scope of the following claims.

For example, the preferred embodiment is described above with reference to twisting a stay wire around a line wire in a knotted fence mesh forming machine. However, it will be appreciated that the preferred embodiment has applications for forming twisted wire joints between other wires in other types of machines.

The components could differ from those shown and described. As an example, in the preferred embodiment the ramp 141 Is formed on the underside of a fixed member 104. Instead, the ramp could be provided on the underside of one of the support plates or the machine bed itself. The latter configuration is shown in FIGS. 20 and 21. Unless described, the features and operation are the same as for the embodiment described above, and like reference numerals are used to indicate like parts, with the addition of 100.

As can be seen, the ramp 204 is a fixed part of the bed 203. As the cutter 235 and support plate 237 are moved to bring the stay wire into a position where it is adjacent to the line wire 102 a, the free end of the stay wire 107 is cut and moved down the ramp 204 to a position in which it will be engaged upon rotation of the rotatable member 205.

The description and drawings describe and show a preferred embodiment rotatable member. Whilst that is the preferred embodiment, it will be appreciated that other shapes could be used while still achieving the desired functionality. For example, the rotatable member could have a different outer body shape, yet could still be provided with a recess and an associated engagement surface to engage and twist the wire about the line wire.

Further, the preferred embodiments show ramp portions for bending the free end of the stay wire prior to rotation of the rotatable member. For some applications, it is not necessary that such a ramp portion is provided. Instead, the transversely extending wire could be pre-bent, or alternatively the transversely extending wire could initially be on an angle relative to the other wire, so as to be engaged and moved by the engagement, surface during rotation of the rotatable member. 

1. An apparatus for twisting a second length of wire around a first length of wire to form a twisted wire joint, the apparatus comprising a rotatable member comprising: an aperture substantially aligned with an axis of rotation of the member and through which a first length of wire may extend; a recess, at least a portion of which is substantially aligned with the aperture; and an engagement surface associated with the recess; wherein the apparatus is configured such that with a first length of wire extending through the aperture and a second length of wire extending across and adjacent to the first length of wire, rotation of the rotatable member will cause the engagement surface to engage with the second length of wire and twist the second length of wire around the first length of wire to form a twisted wire joint at least substantially within the recess and which includes a plurality of full turns of the second length of wire around the first length of wire.
 2. An apparatus as claimed in claim 1, wherein the apparatus is configured to form the twisted wire joint while allowing a remainder part of the second length of wire, other than the part in the twisted wire joint, to remain substantially undeformed.
 3. An apparatus as claimed in claim 2, wherein the apparatus does not require movement of the rotatable member along the first length of wire during the formation of the twisted wire joint or movement of the remainder part of the second length of wire along the first length of wire during the formation of the twisted wire joint.
 4. An apparatus as claimed in claim 1, wherein the engagement surface is configured to direct a free end of the second length of wire in the general direction of the aperture, during the formation of the twisted wire joint.
 5. An apparatus as claimed in claim 4, configured such that the second length of wire will have an initial point of contact with the first length of wire prior to, or as, the rotatable member is rotated, and wherein the second length of wire can substantially maintain its initial point of contact with the first length of wire during the formation of the twisted wire joint, and the twisted wire joint will extend into the recess from the initial point of contact between the first and second lengths of wire.
 6. An apparatus as claimed in claim 5, wherein the recess terminates at a substantially planar surface of the rotatable member, and wherein a portion of the remainder part of the second length of wire can remain substantially in contact with the generally planar surface during formation of the twisted wire joint.
 7. Art apparatus as claimed in claim 4, wherein the engagement surface is angled and extends substantially from an outer edge of the rotatable member toward the aperture in the rotatable member.
 8. An apparatus as claimed in claim 7, wherein the outer edge of the rotatable member defines an engagement portion to initially engage with the second length of wire upon rotation of the rotatable member.
 9. An apparatus as claimed in claim 1, wherein the recess comprises a generally centrally-disposed arcuate wall portion that is positioned adjacent the aperture.
 10. An apparatus as claimed in claim 9, wherein the aperture has a diameter, and the arcuate wall portion has a size sufficiently greater than the diameter of the aperture that the portion of the first wire extending through the aperture is supported during the formation of the twisted wire joint, and sufficient clearance is provided in the arcuate wall portion to enable the twisted wire joint to be formed.
 11. An apparatus as claimed in claim 9, wherein the recess is generally segment-shaped, and wherein a narrow portion of the generally segment-shaped recess is defined by the arcuate portion.
 12. An apparatus as claimed in claim 1, wherein, the engagement surface is defined by a wall portion of the recess.
 13. An apparatus as claimed in claim 1, comprising a positioning member configured to position a free end of the second length of wire such that rotation of the rotatable member will cause the engagement surface of the rotatable member to engage with the second length of wire.
 14. An apparatus as claimed in claim 13, wherein the positioning member is configured to bend a free end of the second length of wire extending beyond a central portion of the rotatable member.
 15. An apparatus as claimed in claim 13, wherein the positioning member comprises a ramp portion that is configured to bend the free end of the second length of wire upon relative movement between the free end of the second length of wire and the positioning member.
 16. An apparatus as claimed in claim 1, comprising a cutting member to cut a free end of the second length of wire prior to rotation of the rotatable member.
 17. An apparatus as claimed in claim 1, further comprising at least one support plate to assist in maintaining the wires adjacent one another during the formation of the twisted wire joint.
 18. An apparatus as claimed in claim 17, wherein the support plate comprises a curved portion to assist in directing a free end of the second length of wire in the general direction of the aperture, upon rotation of the rotatable member.
 19. An apparatus as claimed in claim 1, configured such that the first length of wire remains substantially undeformed during the formation of the twisted wire joint.
 20. A fence mesh forming machine comprising: a machine bed arranged to pass a plurality of substantially parallel line wires therethrough; an apparatus arranged to deliver a stay wire across the line wires; and an apparatus as claimed in claim 1 arranged to twist a free end of the stay wire around one of the line wires to form a twisted wire joint.
 21. A fence mesh, forming machine as claimed in claim 20, wherein, the apparatus is arranged to twist the free end of the stay wire around an outermost line wire of the plurality of line wires.
 22. A fence mesh, forming machine as claimed in claim 20, comprising two apparatuses as claimed in claim 1, arranged to twist the free ends of the stay wire around the two outermost line wires of the plurality of line wires to form twisted wire joints.
 23. A method of twisting a second length of wire around a first length of wire to form a twisted wire joint comprising: providing an apparatus as claimed in claim 1; extending a first length of wire through the aperture of the rotatable member; positioning a second length of wire across and adjacent to the second length of wire; and rotating the rotatable member such that the engagement surface engages with the second length of wire and twists the second length of wire around the first length of wire to form a twisted wire joint at least substantially within the recess of the rotatable member and which includes a plurality of full turns of the second length of wire around the first length of wire.
 24. A method as claimed in claim 23, comprising, prior to rotating the rotatable member, bending a free end of the second length of wire so that it is engaged by the engagement surface upon rotation of the rotatable member. 